yfinance_get_option_chain
AI agents call yfinance_get_option_chain to retrieve information from Yahoo Finance MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool retrieves options chain data (option contracts, strikes, expiries, prices, Greeks, etc.) from Yahoo Finance without making trades, executing arbitrary code, or modifying any data. This is a pure data query operation. Though financial data is involved, the tool does not move money or commit financial obligations—it only reads publicly available market information.
From the tool's definition Tool name 'yfinance_get_option_chain' indicates retrieval of options chain data. The server is explicitly described as fetching 'stock data, news, and other financial information' with no mention of execution, modification, or financial transactions.
Attacks that exploit this kind of access
yfinance_get_option_chain. It is categorised as a Read tool in the Yahoo Finance MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Yahoo Finance MCP Server MCP server in PolicyLayer and add a rule for yfinance_get_option_chain: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Yahoo Finance MCP Server. Nothing to install.
yfinance_get_option_chain is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the yfinance_get_option_chain rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for yfinance_get_option_chain. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
yfinance_get_option_chain is provided by the Yahoo Finance MCP Server MCP server (narumiruna/yfinance-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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